IDENTIFICATION OF GENES AND COMPOUNDS FOR TREATMENT OF CANCER
RELATED APPLICATIONS
This application claims priority to U.S. Provisional App. No. 60/171,728 filed December 22, 1999.
FIELD OF THE INVENTION
The present invention relates to the identification of compounds having an effect on a cell such as a cancer cell. The compounds are identified by performing an assay to detect expression of one or more genes following exposure of the cell to the compound.
BACKGROUND OF THE INVENTION
Compounds are being rapidly developed for treatment or prevention of various disorders in human patients. The birth of the combinatorial chemistry field has provided researchers with a wide variety of potentially useful compounds. Prior to testing and administration to either animal or human subjects, it is advisable to undertake a study of the potential effects of the test compound on the subject. As such, it is useful to have available the capability to rapidly and efficiently measure any such potential effects. For example, if a compound were hypothesized to be useful for preventing cancer, it would be important to ascertain whether the compound is likely to promote another type of disorder, such as a different type of cancer.
Cell adhesion is involved in many different physiological mechanisms. For example, changes in cell adhesion and the remodeling of the extracellular matrix play a critical role in the invasion of malignant tumors. Extracellular matrix degrading proteases such as urokinase- type plasminogen activator (uPA), matrix-type metalloproteinases (MMPs) and membrane- type MMPs (MT-MMPs) have been shown to participate in the remodeling of the extracellular matrix through a proteolytic cascade (Blood, et al. Tumor interactions with the vasculature: angiogenesis and tumor metastasis. Biochem. Biophys. Acta, 1032: 89-118, 1990; Uhm, et al. Mechanisms of glioma invasion: Role of matrix-mettalloproteinases. Can. J. Neurol. Sci., 24: 1-15, 1997). Although their biological activity is highly regulated at the post-transcriptional level, they are regulated at the transcriptional level as well (Matrisian, et al. Stromelysin transin and tumor progression. Semin. Cancer BioL, 1: 121-125, 1990). Transcription factors AP-1 and Ets-1 take part in the induction of uPA and several MMP genes (Matrisan, supra; Nerlov, et al. Essential AP-1 and PEA3 binding elements in the human urokinase enhancer display cell-type specific activity. Oncogene, 6: 1583-1592, 1991). Mitogenic stimulation by growth factors and activation of PKC induce the expression of matrix degrading proteases through the induction of these transcription factors (Matrisan,
supra; Wernert, et al. Stromal expression of c-Etsl transcriptional factor correlates with tumor invasion. Cancer Res., 54: 5683-5688, 1994).
In particular, the role of proteolytic enzymes in glioma invasion has been studied. The expression of MMP-2, MMP-9, MT-MMP, uPA and its receptor has been found in gliomas (Uhm, supra; Yamamoto, et al. Differential expression of membrane-type matrix metalloproteinase and its correlation with gelatinase A activation in human malignant brain tumors in vivo and in vitro. Cancer Res., 56: 384-392, 1996; Gladson, et al. Up-regulation of urokinase and urokinase receptor genes in malignant astrocytoma. Am. J. Pathol., 146: 1150-1160, 1995). MMP-2 activity correlates with the invasiveness of human gliomas in vitro (Uhm, supra) and is largely dependent on post-transcriptional and post-translational modification of the enzyme. The proteolytic activation of MMP-2 by MT-MMP (Yamamoto, supra), and the association between MMP-2 or uPA and integrins plays a critical role in regulating invasivity (Yamamoto, supra; Wei, et al. Regulation of integrin function by the urokinase receptor. Science, 273: 1551-1555, 1996; Brooks, et al. Localization of matrix metalloproteinase MMP-2 to the surface of invasive cells by interaction with integrin αvβ3. Cell, 85: 683-693, 1996). While MMP-2 is constituitively expressed in most tumor cells (Uhm, supra), the expression of other MMPs and uPA can be transcriptionally regulated by growth factors and PKC activators through the transcription factors AP-1 and Ets-1. MMP-1, -3, -7, -9, -10 and uPA genes contain the promoter sequence for AP-1 and PEA3 (Uhm, supra). In fact, a recent study showed that increased expression of uPA, MMP-1, MMP-3 and Ets-1 was found in stromal fibroblasts adjacent to carcinoma cells, while there was little expression of these mRNA within the carcinoma cells themselves (Wernert, supra).
Glycosylation also plays an important role in cell adhesion. Expression of aberrant βl,6 GlcNAc bearing N-glycans, a hallmark of oncogenic transformation, plays an important role in regulating tumor cell adhesion and metastasis (Hakomori, S. Tumor malignancy defined by aberrant glycosylation and sphingo(glyco)lipid metabolism. Cancer Res., 56: 5309-5318, 1996; Asada, et al. Increased expression of highly branched N-glycans at cell surface is correlated with the malignant phenotypes of mouse tumor cells. Cancer Res. 57: 1073-1080, 1997). Increased expression of tri- or tetra-antennary βl,6-GlcNAc bearing N- glycans has been correlated with metastatic potential in rodent tumor models (Asada, supra; Dennis, et al. βl-6 branching of Asn-linked oligosaccharides is directly associated with metastasis. Science, 236: 582-585, 1987) and also has been shown to be a marker of tumor progression in human breast and colon neoplasia (Fernandes, et al. βl-6 branched oligosaccharides as a marker of tumor progression in human breast and colon neoplasia. Cancer Res., 51: 718-723, 1991.). Furthermore, the enzyme responsible for the biosynthesis of βl,6-GlcNAc bearing N-glycans, UDP-N-acetylglucosamine:β-D-mannoside βl,6 N- acetylglucosaminyltransferase V (GnT-V) (EC 2.4.1.155), is regulated by the Ets-1 transcription factor in a human bile duct carcinoma cell line (Kang, et al. Transcriptional
regulation of the N-acetylglucosaminyl-transferase V gene in human bile duct carcinoma cells (HuCC-Tl) is mediated by Ets-1. J. Biol. Chem., 271: 26706-26712, 1996). Recently, it has been shown that βl,6-linked N-glycans are expressed in primary glioma specimens and that a positive correlation exists between the expression of ets-1 and GnT-N in glioma cell lines. While degradation of the extracellular matrix by proteolytic enzymes such as MMPs and uPA has been studied extensively in malignant gliomas, the biological significance of aberrant βl,6-GlcΝAc bearing N-glycans in glioma cells, the product of GnT-N, has not been well characterized. It has been reported that integrins play a key role in glioma invasivity (Demetriou, et al. Reduced contact-inhibition and substratum adhesion in epithelial cells expressing GlcΝAc-transferase N. J. Cell Biol, 130: 383-392, 1995), and that the Ν-glycan component of the integrins modulates their function (Paulus et al. Basement membrane invasion of glioma cells mediated by integrin receptors. J. Neurosurgeiy 80: 515-519, 1994). An increase in the expression of more highly-branched βl,6-GlcΝAc N-linked oligosaccharides is the most commonly observed change found in the N-glycosylation patterns observed in experimental tumor models (Hakomori, supra). Increased βl,6-GlcNAc linked N-glycans, brought about by GnT-N gene transfection into premalignant mink lung epithelial cells, resulted in altered oc5βl and αvβ3 integrins, which in turn caused an increase in cell motility, and, thus, an increase in tumorigenicity (Demetriou, supra). It has been shown that increased expression of βl,6-GlcΝAc N-linked oligosaccharides on α3βl integrin, the predominant integrin found in gliomas (Paulus, supra), can reduce cell adhesion and increase migration and invasivity (data not shown). A direct correlation between increased βl,6-linked branching of complex-type oligosaccharides and metastatic potential has been shown in a variety of tumor models, including cells transformed by DNA viruses such as Polyoma and Rous sarcoma, and oncogenes such as ras (Dennis, 1987, supra). Furthermore, it has been shown that the Ets family of transcription factors plays a critical role in inducing a malignant phenotype in cancer cells that have been transformed by the ras oncogene (Wasylyk, et al. Reversion of Ras transformed cells by Ets transdominant mutants. Oncogene, 9: 3665-3672, 1994). The suppression of endogenous Ets family transcription factor(s) by the transfection of Ets transdominant mutants can reverse malignant phenotypes caused by rαs-mediated transformation in NIH3T3 fibroblasts (Wasylyk, supra). It is thus possible that the Ets family transcription factors are a direct downstream target affected by rαs-mediated transformation. Our results suggest that further downstream target genes, which are regulated by Ets-1 transcription factor and cause malignant phenotypes, are MMP-1, MMP-3 and GnT-N in human gliomas. It has been shown that target genes of ets- 1 can be identified using differential display and whole genome PCR techniques (Robinson, et al. 1997. EES target genes: Identification of Egrl as a target by RNA differential display and whole genome PCR techniques. Proc. Νatl. Acad. Sci. USA, 94: 7170-7175). Novel methods for identifying such target genes are
provided by the present invention, as described below. For example, the present invention provides for regulation of ets-1 expression and identification of concomitantly induced genes. In addition, an assay system for measuring the effects of a compound on expression of one or more genes in a cell. The present invention further provides an assay system for measuring the effect of a compound on the expression of ets-1, MMP-1, MMP-3 and GnT-N in human gliomas. Other advantages of the present invention are described below.
SUMMARY OF THE INVENTION
The present invention relates to reagents and methods for diagnosing and/or treating cancer or other conditions that are affected by one or more members of a panel of genes or the protein products thereof. The present invention also provides methods for the discovery of compounds that effect expression of such sequences, thereby providing candidate compounds for treating and/or preventing cancer or other conditions.
In one embodiment, the present invention provides a method for identifying a compound affecting a cell comprising the steps of contacting a cell with a compound; and detecting expression of a panel of sequences selected from the group consisting of Ets-1, uPA, GnT-N, MMP-1 and MMP-3 in the cell, said panel comprising any combination of the Ets-1, uPA, GnT-N, MMP-1 and MMP-3 sequences; whereby a compound having an effect on expression of any of Ets-1, uPA, GnT-N, MMP-1 and MMP-3 is identified. In a preferred embodiment, the cell is pre-treated with a protein kinase activator prior to contacting the cell. In a more preferred embodiment, the cell is pre-treated with phorbol 12, 13-dibutyrate (PDBu).
In another embodiment, a recombinant DΝA molecule comprising a trancriptional control region, promoter, or regulatory element of a gene selected from the group consisting of Ets-1, GnT-N, uPA, MMP-1 and MMP-3 operably linked to a reporter sequence selected from the group consisting of β-galactosidase, luciferase, green fluorescent protein (GFP), and chloramphenical acetyl transferase (CAT) is provided. In yet another embodiment, the present invention provides a method for identifying a compound affecting a cell comprising contacting a cell with a compound; and detecting expression of a reporter gene functionally linked to a promoter sequence, where the promoter sequence is selected from the group consisting of the Ets-1 promoter, the GnT-N promoter, the uPA promoter, the MMP-1 promoter and the MMP-3 promoter; whereby a compound having an effect on expression directed by the Ets-1 promoter, GnT-N promoter, uPA promoter, MMP-1 promoter and MMP-3 promoter is detected. In yet another embodiment, a recombinant cell comprising a DΝA molecule comprising a reporter sequence functionally joined to an Ets-1 promoter, GnT-N promoter, uPA promoter, MMP-1 promoter, or MMP-3 promoter operably linked to a reporter gene is provided.
In another embodiment, the present invention provides a kit for identifying a compound affecting a cell comprising a solid support; and a recombinant cell comprising a reporter sequence functionally joined to promoter selected from the group consisting of the Ets-1 promoter, the GnT-N promoter, the uPA promoter, the MMP-1 promoter, and the MMP-3; whereby a compound is contacted with the recombinant cell and expression of the reporter sequence is detected.
Other embodiments that would be understood to be within the scope of the present invention are described below.
BRIEF DESCRIPTION OF THE INVENTION
Figure 1. Expression of GnT-V, c-ets-1, and uPA mRNA in human brain tumor cell lines. 20 μg of total RNA per lane were used for Northern analysis. Lanes 1-6: human glioma cell lines, SW1088, D-54MG, U-373MG, U-87MG, U-118MG and SNB-19, respectively. Lanes 7-10: human neuroblastoma cell lines, LAN-5, IMR-32, SKN-SH and SKN-MC, respectively. Levels of GnT-V mRNA (panel A), c-ets-1 mRNA expression (panel B), and uPA (panel C) are well correlated. Ethidium bromide staining of total RNA (panel D). Figure 2. Expression of Ets-1 protein in glioma cell lines. Western blot of Ets-1 protein using monoclonal anti-Ets-1 antibody. Lanes 1-5; human glioma cell lines, SW1088, U- 118MG, U-373MG, U-87MG, and D-54MG, respectively. Lanes 6-9; human neuroblastoma cell lines, SKN-SH, SKN-MC, LAN-5 and IMR-32, respectively.
Figure 3. Expression of MMPs in human brain tumor cell lines. 20 μg of total RNA per lane were used for Northern analysis. Lanes 1-2: normal adult human brain, lanes 3-8: human glioma cell lines, SW1088, D-54MG, U-373MG, U-87MG, U-118MG and SNB-19, respectively. Lanes 9-12: human neuroblastoma cell lines, LAN-5, IMR 32, SKN-SH and SKN-MC, respectively. MMP-1 mRNA is expressed in SW1088, U-87MG, U-118MG glioma cell lines and SKN-SH neuroblastoma cells (panel A), while MMP-3 mRNA is expressed in SW1088, D-54MG, U-87MG, U-118MG glioma cell lines and SKN-SH neuroblastoma cells (panel B). MMP-10 mRNA expression was found only in SW1088 and U-87MG glioma cells (panel C). Ethidium bromide staining of total RNA (panel D). Figure 4. Concomitant induction of GnT-V, c-ets-1, uPA, MMP-1, MMP-3 mRNA by PDBU, and suppression of PDBu-mediated gene transcription by a MAPKK inhibitor. SNB-19 cells were incubated with 150 nM PDBu for 0, 6, 12, 18, and 24 hr, and the cells were harvested for Northern analyses; 20 μg of total RNA per lane were used. Lanes 1-5: SNB-19 cells incubated with 150 nM PDBu for 0, 6, 12, 18, and 24 hr, respectively. Lane 6: SNB-19 cells incubated with 150 nM PDBu for 24 hr in the presence of 15 μM MAPKK inhibitor, 2'-amino-3'-methoxyflavone. Panels A-E show the expression of GnT-V, c-ets-1, uPA, MMP-1, and MMP-3, respectively. Panel F shows total RNA staining by ethidium bromide. The marked induction of GnT-N, c-ets-1, uPA, MMP-1, and MMP-3 gene
expression at 24 hr incubation was associated with the concomitant induction of ets-1 mRNA. The induction was completely abolished by the addition of the MAPKK inhibitor. Figure 5. Increased expression of GnT-V and uPA mRNA following induction of ets-1 mRNA in glioma cells. The pcDNA4/TO/c-ets-l and pcDNA6/TR co-transfected SNB-19 cells (clones 1 and 2) were incubated in the presence of 2 μg/ml tetracycline for 24 hr to induce the transfected c-ets-1 expression. Both the induced (lanes labeled "+" indicating addition of tetracycline) and control cells (lanes labeled "-", without tetracycline) were harvested for Northern analyses; 15 μg of total RNA per lane were used. The blot was hybridized by both radiolabeled GnT-V and ets-1 cDNA probes. Induction of ets-1 (panel A) resulted in increased expression of GnT-V and uPA mRNA in transfectants B3, B7, and B9 (panel B). Total RNA staining by ethidium bromide is shown for each sample in panel C. Figure 6. Results of High-Flow Through RT-PCR Assay Using SNB19 Glioma Cells. Figure 7. Results of High-Flow Through RT-PCR Assay Using U87 cDNA.
DETAILED DESCRIPTION OF THE INVENTION Within this application, unless otherwise stated, definitions of the terms and illustration of the techniques of this application may be found in any of several well-known references such as: Sambrook, J., et al, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press (1989); Goeddel, D., ed., Gene Expression Technology, Methods in Enzymology, Vol. 185, Academic Press, San Diego, CA (1991); "Guide to Protein Purification" in Deutshcer, M.P., ed., Methods in Enzymology, Academic Press, San Diego, CA (1989); Innis, et al., PCR Protocols: A Guide to Methods and Applications, Academic Press, San Diego, CA (1990); Freshney, R.I., Culture of Animal Cells: A Manual of Basic Technique, 2nd Ed., Alan Liss, Inc. New York, NY (1987); Murray, E.J., ed., Gene Transfer and Expression Protocols, pp. 109-128, The Humana Press Inc., Clifton, NJ and Lewin, B., Genes VI, Oxford University Press, New York (1997). All references cited within this application are hereby incorporated by reference.
For the purposes of this application, a transcriptional regulatory region is defined as any region of a gene involved in regulating transcription of a gene, including but not limited to promoters, enhancers and repressors. A transcriptional regulatory element is defined as any element involved in regulating transcription of a gene, including but not limited to promoters, enhancers and repressors. A promoter is a regulatory sequence of DNA that is involved in the binding of RNA polymerase to initiate transcription of a gene. A gene is a segment of DNA involved in producing a peptide, polypeptide or protein, including the coding region, non-coding regions preceding ("leader") and following ("trailer") the coding region, as well as intervening non-coding sequences ("introns") between individual coding segments ("exons"). Coding refers to the representation of amino acids, start and stop signals
in a three base "triplet" code. Promoters are often upstream ("5' to") the transcription initiation site of the corresponding gene. Other regulatory sequences of DNA in addition to promoters are known, including sequences involved with the binding of transcription factors, including response elements that are the DNA sequences bound by inducible factors. Enhancers comprise yet another group of regulatory sequences of DNA that can increase the utilization of promoters, and can function in either orientation (5 '-3' or 3 '-5') and in any location (upstream or downstream) relative to the promoter. Preferably, the regulatory sequence has a positive activity, i.e., binding of an endogeneous ligand (e.g. a transcription factor) to the regulatory sequence increases transcription, thereby resulting in increased expression of the corresponding target gene. The term operably linked or functionally linked refers to the combination of a first nucleic acid fragment representing a transcriptional control region having activity in a cell joined to a second nucleic acid fragment encoding a reporter or effector gene such that expression of said reporter or effector gene is influenced by the presence of said transcriptional control region. A responsive element is a portion of a transcriptional control region that induces expression of a nucleotide sequence. There may be multiple responsive elements within a single transcriptional control region and each of these elements may function independently of any other elements of that transcriptional control region. Thus, a responsive element may be incorporated into a reporter gene vector independent from the remainder of the transcriptional control region from which it is derived and function to drive expression of the reporter gene under the proper conditions.
Cancer is defined herein as any cellular malignancy for which a loss of normal cellular controls results in unregulated growth, lack of differentiation, and increased ability to invade local tissues and metastasize. Cancer may develop in any tissue of any organ at any age. Cancer may be an inherited disorder or caused by environmental factors or infectious agents; it may also result from a combination of these. For the purposes of utilizing the present invention, the term cancer includes both neoplasms and premalignant cells.
Brain cancer is defined herein as any cancer involving a cell of neural origin. Examples of brain cancers include but are not limited to intracranial neoplasms such as those of the skull (i.e., osteoma, hemangioma, granuloma, xanthoma, osteitis deformans), the meninges (i.e., meningioma, sarcoma, gliomatosis), the cranial nerves (i.e., glioma of the optic nerve, schwannoma), the neuroglia (i.e., gliomas) and ependyma (i.e., ependymomas), the pituitary or pineal body (i.e., pituitary adenoma, pinealoma), and those of congenital origin (i.e., craniopharyngioma, chordoma, ge minoma, teratoma, dermoid cyst, angioma, hemangioblastoma) as well as those of metastatic origin.
In one embodiment, the present invention provides a method for detecting expression in a cell of at least one member of a panel of nucleotide sequences or fragments thereof corresponding to ets-1, GnT-V, urokinase-type plasminogen activator (uPA), matrix
metalloproteinase- 1 ("MMP-1") or matrix metalloproteinase-3 ("MMP-3") nucleotide sequences. As altered expression of these sequences is associated with changes in cancer cells, including increased invasivity, the method is useful for identifying cells that are cancerous or have the potential of becoming cancerous. In addition, the assay is useful for identifying compounds that drive the cells toward a cancerous state following interaction with the cell. The method is also useful for identifying compounds that affect expression of one or more of ets-1 (also referred to as "c-ets-1"), GnT-V, uPA, MMP-1, MMP-3.
In one embodiment, the presence of cancerous cells within a biological sample of a patient is determined. A biological sample such as a tissue or tumor sample, blood, saliva or other bodily tissue or fluid is collected from a patient suspected of having cancer, for example. The levels at which one or more nucleotide sequences related to ets-1, GnT-V, uPA, MMP-1, MMP-3 are expressed is then determined. The levels of expression are compared to a control sample, such as a patient that does not have cancer or a previous sample taken from the patient (i.e., prior to development of cancer, if possible). The control sample may also represent a sample taken prior to treatment with a particular therapeutic regimen. Increased expression of any or all of the nucleotide sequences is indicative of the presence of cancer. Decreased expression may also be indicative of a particular condition. This assay is also useful for detection of cancerous cells by detecting protein levels within the patient where instead of detecting nucleotide sequences, the protein products of the nucleotide sequences are detected by, for example, western blot.
In a preferred embodiment, the panel comprises any combination of nucleotide sequences related to ets-1, GnT-V, uPA, MMP-1 and MMP-3 nucleotide sequences. For example, the panel may comprise the combination of ets-1 and GnT-V; ets-1 and uPA; ets-1 and MMP-1; ets-1 and MMP-3; GnT-V and uPA; GnT-V and MMP-1; GnT-V and MMP-3; MMP-1 and uPA; MMP-1 and MMP-3; uPA and MMP-3. Other suitable combinations of ets-1, GnT-V, uPA, MMP-1 and MMP-3 are also encompassed by the method provided herein. In addition, nucleotide sequences corresponding to ets-1, GnT-V, uPA, MMP-1 or MMP-3 may be assayed in a single assay (i.e., mixed PCR) or in separate assays. It is also contemplated that ets-1, GnT-V, uPA, MMP-1 or MMP-3 may be assayed alone without consideration of the other sequences. Additionally contemplated is the assay of one or more of ets-1, GnT-V, uPA, MMP-1 or MMP-3 sequences in combination with other sequences to generate useful assay systems. Suitable other sequences would be known by those of skill in the art.
The invention further provides for a method of ascertaining propensity for malignancy, monitoring the progress of chemotherapy or other anticancer therapy, screening for recurrence of cancer, or other similar detection of present or potential cancer, by detecting expression of at least one of Ets-1, GnT-V, MMP-1 or MMP-3 in the cells of a patient undergoing treatment. The present invention provides for a method for ascertaining the
propensity for malignant phenotype of cells in a biological sample, said method comprising assaying a biological sample to be tested for a signal indicating the presence of a nucleic acid, such as an mRNA, corresponding to Ets-1, GnT-V, uPA, MMP-1 or MMP-3. In a preferred embodiment, the nucleic acid corresponds to Ets-1, GnT-V, uPA, MMP-1, and / or MMP-3, as well as fragments thereof and sequences complementary thereto.
The method is also useful to determine whether a particular treatment for cancer, such as radiation, chemotherapy or other treatment, is affecting cancer cells and / or optimized for the particular patient. For example, an assay is performed on a biological sample from a patient to detect expression of Ets-1, GnT-V, uPA, MMP-1 or MMP-3 prior to, during, and after treatment to monitor for the continued presence, return of, or affect on cancerous cells of the patient. Such screening assays are designed to detect for the presence of cells expressing a nucleic acid corresponding to Ets-1, GnT-V, uPA, MMP-1 or MMP-3, as well as fragments thereof and sequences complementary thereto, as an indicator of the possible tumor recurrence or that the treatment regimen is not optimized, for example. For instance, in a patient in whom Ets-1 expression was detected in tumor cells prior to treatment, and in whom ets-1 expression was detected at lower levels during or following treatment, re-expression of ets-1 following treatment may indicate a resumption of growth by the cancer cells.
Related to the use described above, the methods and compositions of the present invention allow for a therapeutic prediction of the efficacy of any contemplated therapy or therapeutic on the cancer. By determining the characteristic gene expression features, and testing cells for modulation of such gene expression, it is possible to determine the potential responsiveness of the target brain cancer to the proposed therapeutic. For example, a biological sample containing a tumor cell is removed from a patient. The sample is then exposed to a treatment protocol (i.e., a chemotherapeutic compound) to be used to treat the patient's tumor. The sample is then assayed for changes in the expression of ets-1, GnT-V, uPA, MMP-1 or MMP-3. An increase in the expression of any of ets-1, GnT-V, uPA, MMP- 1 or MMP-3 suggests that the compound may not be useful in treating the patient's tumor. In contrast, a decrease in the expression of any of the sequences suggests that the compound may be useful in treating the patient's tumor. Thus, the assay quickly identifies those treatments having the greatest potential for treating the patient's cancer. In a similar way, such methods allow for identifying suitable combination therapies.
Genetic screening is also made possible, as detecting mutations within the ets-1, GnT- V, uPA, MMP-1 or MMP-3 genes. Using the sequences or the transcriptional control elements of such genes, it is possible to detect and identify persons with a potential predisposition for cancer, and thus bring medical monitoring early in life. For instance, a tissue-based assay may provide the ability to predict persons susceptible to cancer based on their relative levels of expression of Ets-1, GnT-V, MMP-1 or MMP-3.
Also contemplated herein are recombinant DNA constructs comprising a transcriptional regulatory region, promoter or other regulatory element (i.e., enhancer) of one or more of the ets-1, GnT-V, uPA, MMP-1 and MMP-3 genes. For example, the present invention provides a recombinant DNA molecule comprising a transcription control region of Ets-1, GnT-V, uPA, MMP-1 and / or MMP-3 gene may be operably linked to a reporter gene such as β-galactosidase (β-gal), luciferase (LUC), green fluorescent protein (GFP), red fluorescent protein (RFP), yellow fluorescent protein (YFP), chloramphenical acetyl transferase (CAT), or other reporter gene. Many reporter genes are available to the skilled artisan that would be suitable for the purposes of this invention. Preferably, the transcriptional regulatory region, promoter or regulatory element from either or both of the Ets-1, GnT-V, uPA, MMP-1 and / or MMP-3 is operably linked to a nucleotide sequence encoding the reporter protein in an expression vector construct. The construct is then transiently or stably transfected into a cell. The cell is then exposed to a treatment protocol (i.e., a chemotherapeutic compound) that affects, by activating or inhibiting, the activity of the transcriptional regulatory region, promoter or regulatory element, resulting in increased or decreased expression of the reporter gene within the cell. Expression of the reporter gene is determined by detection of the reporter protein by, for instance, a luciferase assay where the reporter sequence encodes luciferase. Many types of reporter gene assays are available to the skilled artisan. In this manner, a system is provided whereby the potential influence of a particular condition or compound on gene expression in a cell is determined. In addition, the system may be configured to provide a high-throughput assay for identifying compounds that increase or decrease expression of genes involved in cancer. As such, the method is useful for drug discovery and drug safety evaluations.
For instance, a recombinant DNA molecule having an ets-1 promoter operably linked to β-gal is constructed. The construct is transfected into a cell line and the cells are contacted with a test compound. This results in activation of the ets-1 promoter and increased expression of β-gal in the cell, which is determined by performing a standard β-gal assay. These results, then, indicate that the compound being tested activates the ets-1 promoter. It is important to make such a determination when analyzing a test compound intended to be used to treat a patient, for example. Where a compound causes activation of the ets-1 promoter, further analysis should be performed to ensure the compound will not detrimentally alter the condition of the patient.
The reagents and methodologies of the present invention provide several assay systems for identifying genes and proteins whose expression is influenced by ets-1. One such system comprises an inducible ets-1 expression construct that is transiently or stably transfected into a cell. Ets-1 expression is then induced and the sequences expressed as a result of ets-1 induction are identified. The sequences may be identified using a method such as differential display analysis and cloning, for example. To accomplish this, the sequences
expressed under uninduced conditions (i.e., low level or absent ets-1 expression) are compared to those expressed following induction of ets-1 expression. In this manner, genes that are influenced by ets-1 are identified.
For example, a cell is transfected with a DNA construct having the ets-1 coding sequence under the transcriptional control of a tetracycline-responsive element, such as TetO. The cell is cultured in the presence of presence of tetracycline, which inhibits expression of ets-1 from the construct. When tetracycline is removed from the cell culture, ets-1 is expressed from the construct. The genes that are expressed following ets-1 expression are then compared to those expressed while ets-1 expression from the construct is repressed by the presence of tetracycline in the culture medium. Genes that are expressed following induction of ets-1 expression and are not expressed prior to induction represent those genes that are either directly or indirectly under the control of ets-1. These genes may be identified using differential display analysis, cloning or using a "DNA chip", for example, and are those considered "ets-1 inducible" . The present invention further provides an assay for identifying a compound that promotes or inhibits the activity of a cell. The activity of the cell may cause the cell to become more or less likely to become cancerous following exposure to the compound. It is of interest to be able to make a determination in either situation. The method comprises contacting a cell with a compound and detecting expression of one or more nucleotide sequences selected from a panel of sequences. In a preferred embodiment, the panel comprises one or more members that correspond by sequence similarity to Ets-1, GnT-V, uPA, MMP-1 or MMP-3. Preferably, the panel members have sequence similarity to at least Ets-1, GnT-V, or uPA. The level of expression of a panel member is determined following exposure to the compound and is then compared to the levels of expression in unexposed cells. A compound that affects a cell is one that causes an increase or decrease in expression of Ets-1, GnT-V, uPA, MMP-1 or MMP-3. If expression of a panel member is increased following exposure to the compound, it is likely that the compound drives the cell toward the cancerous state. If expression of a panel member is decreased or remains unchanged following exposure to the compound, it is likely that the compound does not drive the cell toward the cancerous state. The expression of Ets-1, GnT-V, uPA, MMP-1 or MMP-3 may be determined in a combination assay (i.e., mixed PCR) or in separate assays.
Certain embodiments of this invention required detection of nucleic acids, for which many methods are available to the skilled artisan. Detection of a nucleic acid may be accomplished using any of several techniques available to one skilled in the art such as northern blot (Alwine, et al. Proc. Natl. Acad. Sci. 74:5350 and as described herein), RNase protection (Melton, et al. Nuc. Acids Res. 12:7035 and as described in the 1998 catalog of A bion, Inc., Austin, TX), RT-PCR (Berchtold, et al. Nuc. Acids. Res. 17:453), quantitative
PCR, or the nuclear run-on assay. Instructions for the design and use of such assays are well- known and widely available in the art.
The RNase protection assay may be utilized in the present invention by hybridizing multiple DNA probes corresponding to a one or more members of a panel of sequences to mRNA isolated from a cell exposed to a compound. In a preferred embodiment, the panel is selected from the Ets-1, GnT-V, uPA, MMP-1 and MMP-3 sequences. In another preferred embodiment, multiple DNA probes capable of hybridizing to mRNA corresponding to a reporter sequence under the transcriptional control of a "compound-responsive" transcriptional control region may be utilized. Exemplary reporter sequences comprise β- galactosidase, luciferase, green fluorescent protein, red fluorescent protein, yellow fluorescent protein, or chloramphenicol acetyltransf erase (CAT).
It is also possible to accomplish detection of a nucleic acid using a "DNA chip" . A DNA chip would be useful for identifying sequences that are regulated by ets-1 or by a particular compound, such as a chemotherapeutic drug. In one embodiment, a cell line is provided in which ets-1 is inducible. The nucleic acids that are expressed in the absence of inducible ets-1 expression are compared to the nucleic acids expressed following induction of ets-1 expression. Those sequences showing increased or decreased expression following induction of ets-1 are "ets-1 inducible".
In a similar manner, the nucleic acids expressed before and after exposure of a cell to a particular compound or combination of compounds are determined using a DNA chip. In a preferred embodiment, the sequences affixed to the chip correspond to Ets-1, GnT-V, uPA, MMP-1 or MMP-3. In such a manner, the expression of these sequences following exposure to a compound may be quickly ascertained.
Similar to the methods described above regarding nucleic acids, it is further contemplated to detect protein levels as a reflection of gene expression. Detecting proteins may also allow the investigator to identify compounds that affect protein expression or function without affecting gene expression. In certain embodiments, the present invention provides for detection of a protein, for which many methods are available to the skilled artisan. For instance, in certain embodiments the present invention provides for detection of a protein, polypeptide or fragment thereof encoded by the ets-1, GnT-V, uPA, MMP-1 or MMP-3 genes. It is particularly useful in such instance to utilize an antibody having the ability to bind to a ets-1, GnT-V, uPA, MMP-1 or MMP-3 protein, polypeptide or fragment thereof (collectively referred to herein as "polypeptide").
An antibody of the present invention immunoreacts with a protein, polypeptide or fragment thereof encoded by a nucleic acid that is expressed in a cancer cell. Preferably, the nucleic acid is substantially identical to a sequence of Ets-1, GnT-V, uPA, MMP-1 or MMP- 3, sequences complementary thereto, or fragments thereof. Preferably, an antibody further immunoreacts with the protein, polypeptide or fragment thereof in situ, i.e., in a tissue
section, on a western blot or by immunoprecipitation. Thus, the invention describes an antibody that immunoreacts a recombinant protein corresponding essentially to ets-1, GnT-V, uPA, MMP-1 or MMP-3 nucleic acid coding sequences or fragments thereof, and more preferably also reacts with a native protein in situ in a tissue section. An antibody of the present invention is typically produced by immunizing a mammal with an inoculum containing a polypeptide of this invention and thereby induce in the mammal antibody molecules having immunospecificity for immunizing polypeptide. The antibody molecules are then collected from the mammal and isolated to the extent desired by well known techniques such as, for example, by using DEAE Sephadex or Protein G to obtain the IgG fraction.
Exemplary antibody molecules for use in the diagnostic methods and systems of the present invention are intact immunoglobulin molecules, substantially intact immunoglobulin molecules and those portions of an immunoglobulin molecule that contain the paratope, including those portions known in the art as Fab, Fab', F(ab')2 and F(v). Fab and F(ab')2 portions of antibodies are prepared by the proteolytic reaction of papain and pepsin, respectively, on substantially intact antibodies by methods that are well known. (See for example, U.S. Patent No. 4,342,566 to Theofilopolous and Dixon.) Fab' antibody portions are also well known and are produced from F(ab')2 portions followed by reduction of the disulfide bonds linking the two heavy reduction of the disulfide bonds linking the two heavy chain portions as with mercaptoethanol, and followed by alkylation of the resulting protein mercaptan with a reagent such as iodoacetamide. An antibody containing intact antibody molecules are preferred, and are utilized as illustrative herein.
The preparation of antibodies against a polypeptide is well known in the art. (See Staudt et al., J. Exp. Med.. 157:687-704 (1983), or the teachings of Sutcliffe, J.G., as described in United States Patent No. 4,900,811, the teaching of which are hereby incorporated by reference.) Briefly, to produce a peptide antibody composition of this invention, a laboratory mammal is inoculated with an immunologically effective amount of a polypeptide of this invention typically as present in a vaccine of the present invention. The anti-polypeptide antibody molecules thereby induced are then collected from the mammal and those immunospecific for both a polypeptide and the corresponding recombinant protein are isolated to the extent desired by well known techniques such as, for example, by immunoaffinity chromatography.
To enhance the specificity of the antibody, the antibodies are preferably purified by immunoaffinity chromatography using solid phase-affixed immunizing polypeptide. The antibody is contacted with the solid phase-affixed immunizing polypeptide for a period of time sufficient for the polypeptide to immunoreact with the antibody molecules to form a solid phase-affixed immunocomplex. The bound antibodies are separated from the complex by standard techniques.
For a polypeptide that contains fewer than about 35 amino acid residues, it is preferable to use the peptide bound to a carrier for the purpose of inducing the production of antibodies. One or more additional amino acid residues can be added to the amino- or carboxy-termini of the polypeptide to assist in binding the polypeptide to a carrier. Cysteine residues added at the amino- or carboxy-termini of the polypeptide have been found to be particularly useful for forming conjugates via disulfide bonds. However, other methods well known in the art for preparing conjugates can also be used. The techniques of polypeptide conjugation or coupling through activated functional groups presently known in the art are particularly applicable. See, for example, Aurameas, et al., Scand. J. Immunol.. Vol. 8, Suppl. 7:7-23 (1978) and U.S. Patent No. 4,493,795, No. 3,791,932 and No. 3,839,153. In addition, a site-directed coupling reaction can be carried out so that any loss of activity due to polypeptide orientation after coupling can be minimized. See, for example, Rodwell et al., Biotech.. 3:889-894 (1985), and U.S. Patent No. 4,671,958. Exemplary additional linking procedures include the use of Michael addition reaction products, di-aldehydes such as glutaraldehyde, Klipstein, et al., J. Infect. Pis.. 147:318-326 (1983) and the like, or the use of carbodiimide technology as in the use of a water-soluble carbodiimide to form amide links to the carrier. Alternatively, the heterobifunctional cross-linker SPDP (N-succinimidyl-3-(2- pyridyldithio) proprionate)) can be used to conjugate peptides, in which a carboxy-terminal cysteine has been introduced. Useful carriers are well known in the art, and are generally proteins themselves.
Exemplary of such carriers are keyhole limpet hemocyanin (KLH), edestin, thyroglobulin, albumins such as bovine serum albumin (BSA) or human serum albumin (HSA), red blood cells such as sheep erythrocytes (SRBC), tetanus toxoid, cholera toxoid as well as polyamino acids such as poly D-lysine:D-glutamic acid, and the like. The choice of carrier is more dependent upon the ultimate use of the inoculum and is based upon criteria not particularly involved in the present invention. For example, a carrier that does not generate an untoward reaction in the particular animal to be inoculated should be selected.
The present inoculum contains an effective, immunogenic amount of a polypeptide, typically as a conjugate linked to a carrier. The effective amount of polypeptide per unit dose sufficient to induce an immune response to the immunizing polypeptide depends, among other things, on the species of animal inoculated, the body weight of the animal and the chosen inoculation regimen is well known in the art. Inocula typically contain polypeptide concentrations of about 10 micrograms (μg) to about 500 milligrams (mg) per inoculation (dose), preferably about 50 micrograms to about 50 milligrams per dose. The term "unit dose" as it pertains to the inocula refers to physically discrete units suitable as unitary dosages for animals, each unit containing a predetermined quantity of active material calculated to produce the desired immunogenic effect in association with the required diluent; i.e., carrier, or vehicle. The specifications for the novel unit dose of an inoculum of this invention are
dictated by and are directly dependent on (a) the unique characteristics of the active material and the particular immunologic effect to be achieved, and (b) the limitations inherent in the art of compounding such active material for immunologic use in animals, as disclosed in detail herein, these being features of the present invention. Inocula are typically prepared from the dried solid polypeptide-conjugate by dispersing the polypeptide-conjugate in a physiologically tolerable (acceptable) diluent such as water, saline or phosphate-buffered saline to form an aqueous composition. Inocula can also include an adjuvant as part of the diluent. Adjuvants such as complete Freund's adjuvant (CFA), incomplete Freund's adjuvant (IF A) and alum are materials well known in the art, and are available commercially from several sources.
The antibody so produced can be used, inter alia, in the methods and systems of the present invention to detect a polypeptide in a sample such as a tissue section or body fluid sample. Anti-polypeptide antibodies that inhibit function of the polypeptide can also be used in vivo in therapeutic methods as described herein. A preferred anti-polypeptide antibody is a monoclonal antibody. The phrase "monoclonal antibody" in its various grammatical forms refers to a population of antibody molecules that contain only one species of antibody combining site capable of immunoreacting with a particular epitope. A monoclonal antibody thus typically displays a single binding affinity for any epitope with which it immunoreacts. A monoclonal antibody may therefore contain an antibody molecule having a plurality of antibody combining sites, each immunospecific for a different epitope, e.g., a bispecific monoclonal antibody. A preferred monoclonal antibody of this invention comprises antibody molecules that immunoreact with a polypeptide of the present invention. More preferably, the monoclonal antibody also immunoreacts with recombinantly produced whole protein.
A monoclonal antibody is typically composed of antibodies produced by clones of a single cell called a hybridoma that secretes (produces) only one kind of antibody molecule. The hybridoma cell is formed by fusing an antibody-producing cell and a myeloma or other self-perpetuating cell line. The preparation of such antibodies was first described by Kohler and Milstein, Nature. 256:495-497 (1975), the description of which is incorporated by reference. The hybridoma supernates so prepared can be screened for the presence of antibody molecules that immunoreact with a polypeptide.
Briefly, to form the hybridoma from which the monoclonal antibody composition is produced, a myeloma or other self-perpetuating cell line is fused with lymphocytes obtained from the spleen of a mammal hyperimmunized with a antigen, such as is present in a ets-1, GnT-V, uPA, MMP-1 or MMP-3 polypeptide described herein. The polypeptide-induced hybridoma technology is described by Niman et al, Proc. Natl. Acad. Sci., USA. 80:4949- 4953 (1983), the description of which is incorporated herein by reference. It is preferred that the myeloma cell line used to prepare a hybridoma be from the same species as the lymphocytes. Typically, a mouse of the strain 129 G1X+ is the preferred mammal. Suitable
mouse myelomas for use in the present invention include the hypoxanthine-aminopterin- thymidine-sensitive (HAT) cell lines P3X63-Ag8.653, and Sρ2/0-Agl4 that are available from the American Type Culture Collection, Rockville, MD, under the designations CRL 1580 and CRL 1581, respectively. Splenocytes are typically fused with myeloma cells using polyethylene glycol (PEG) 1500. Fused hybrids are selected by their sensitivity to HAT. Hybridomas producing a monoclonal antibody of this invention are identified using the enzyme linked immunosorbent assay (ELISA) described in the Examples.
A monoclonal antibody of the present invention can also be produced by initiating a monoclonal hybridoma culture comprising a nutrient medium containing a hybridoma that produces and secretes antibody molecules of the appropriate polypeptide specificity. The culture is maintained under conditions and for a time period sufficient for the hybridoma to secrete the antibody molecules into the medium. The antibody-containing medium is then collected. The antibody molecules can then be further isolated by well known techniques. Media useful for the preparation of these compositions are both well known in the art and commercially available and include synthetic culture media, inbred mice and the like. An exemplary synthetic medium is Dulbecco's Minimal Essential Medium (DMEM; Dulbecco et al., Virol. 8:396 (1959)) supplemented with 4.5 gm/1 glucose, 20 mM glutamine, and 20% fetal calf serum. An exemplary inbred mouse strain is the Balb/c. Other methods of producing a monoclonal antibody, a hybridoma cell, or a hybridoma cell culture are also well known. (See, for example, The method of isolating monoclonal antibodies from an immuno logical repertoire, as described by Sastry, et al., Proc. Natl. Acad. Sci. USA. 86:5728-5732 (1989); and Huse et al, Science, 246:1275-1281 (1989)).
The monoclonal antibodies of this invention can be used in the same manner as disclosed herein for antibodies of the present invention. For example, the monoclonal antibody can be used in the therapeutic, diagnostic or in vitro methods disclosed herein where immunoreaction with ets-1, GnT-V, uPA, MMP-1 and / or MMP-3 is desired. Also contemplated by this invention is the hybridoma cell, and cultures containing a hybridoma cell that produce a monoclonal antibody of this invention.
It is also possible to isolate antibodies reactive against polypeptides of the instant invention using phage display techniques. Display of antibody fragments on the surface of viruses which infect bacteria (bacteriophage or phage) makes it possible to produce human sFvs with a wide range of affinities and kinetic characteristics. To display antibody fragments on the surface of phage (phage display), an antibody fragment gene is inserted into the gene encoding a phage surface protein (pill) and the antibody fragment-pIII fusion protein is expressed on the phage surface (McCafferty et al. (1990) Nature, 348: 552-554; Hoogenboom et al. (1991) Nucleic Acids Res., 19: 4133-4137). For example, a sFv gene coding for the V.sub.H and V.sub.L domains of an anti-lysozyme antibody (D1.3) was inserted into the phage gene III resulting in the production of phage with the DI.3 sFv joined to the N-terminus
of pill thereby producing a "fusion" phage capable of binding lysozyme (McCafferty et al (1990) Nature, 348: 552-554). The skilled artisan may also refer to Clackson et al. (1991) Nature, 352: 624-628), (Marks et al. (1992) Bio/Technology, 10: 779-783), Marks et al Bio/Technology, 10: 779-785 (1992) for further guidance. In the instant case, the antibody fragment gene is isolated from the immunized mammal, and inserted into the phage display system. Phage containing antibodies reactive to the polypeptide are then isolated and characterized using well-known techniques. Kits and services are available for generating antibodies by phage display from well-known sources such as Cambridge Antibody Technology Group pic (United Kingdom). In yet another embodiment, the present invention comprises a kit for detennining the effect of a compound on gene expression within a cell. The kit may comprise packaged reagents such as a panel of independent or paired nucleic acid molecules specific for the detection of the expression of specific nucleic acid sequences corresponding to specific species of nucleic acid sequences encoding proteins of interest. Instructions for use of the packaged reagent(s) are also typically included. As used herein, the term "package" refers to a solid matrix or material such as glass, plastic (e.g., polyethylene, polypropylene or polycarbonate), paper, foil and the like capable of holding within fixed limits a polyamide of the present invention. "Instructions for use" typically include a tangible expression describing the reagent concentration or at least one assay method parameter such as the relative amounts of reagent and sample to be admixed, maintenance time periods for reagent or sample admixtures, temperature, buffer conditions and the like. The kit may also include a cell line for testing the effect of a compound on expression of a sequence within the cell. The kit may further comprise a cellular activating compound such as a phorbol ester. In one embodiment, the kit provides for enzyme-mediated nucleic acid amplification such as the polymerase chain reaction (PCR) in which a pair of nucleic acid molecules (i.e., primers) allowing for amplification of a nucleic acid sequence encoding a member of a panel of genes. In one embodiment, a kit for identifying a compound affecting a cell comprising a solid support; a recombinant cell comprising a reporter sequence functionally joined to transcriptional control region, promoter, or regulatory element such as the Ets-1 promoter, the GnT-V promoter, the uPA promoter, the MMP-1 promoter, and the MMP-3 promoter whereby a compound is contacted with the recombinant cell and expression of the reporter sequence is detected.
In another embodiment, the present invention provides a compound identified by its ability to affect the expression or function of one or more of ets-1, GnT-V, uPA, MMP-1 or MMP-3. The compounds of this invention may be formulated into diagnostic and therapeutic compositions for in vivo or in vitro use. Representative methods of formulation may be found in Remington: The Science and Practice of Pharmacy, 19th ed., Mack Publishing Co., Easton, PA (1995). For in vivo use, the compound may be incorporated into a physiologically acceptable pharmaceutical composition that is administered to a patient in
need of treatment or an animal for medical or research purposes. The composition comprises pharmaceutically acceptable carriers, excipients, adjuvants, stabilizers, and vehicles. The composition may be in solid, liquid, gel, or aerosol form. The composition of the present invention may be administered in various dosage foπns orally, parentally, by inhalation spray, rectally, or topically. The term parenteral as used herein includes, subcutaneous, intravenous, intramuscular, intrasternal, infusion techniques or intraperitoneally.
The selection of the precise concentration, composition, and delivery regimen is influenced by, inter alia, the specific pharmacological properties of the particular selected compound, the intended use, the nature and severity of the condition being treated or diagnosed, the age, weight, gender, physical condition and mental acuity of the intended recipient as well as the route of administration. Such considerations are within the purview of the skilled artisan. Thus, the dosage regimen may vary widely, but can be determined routinely using standard methods.
The pharmaceutically active compounds (i.e., compounds) of this invention can be processed in accordance with conventional methods of pharmacy to produce medicinal agents for administration to patients, including humans and other mammals. For oral administration, the pharmaceutical composition may be in the form of, for example, a capsule, a tablet, a suspension, or liquid. The pharmaceutical composition is preferably made in the form of a dosage unit containing a given amount of a compound. A suitable daily dose for a human or other mammal may vary widely depending on the condition of the patient and other factors, but, once again, can be deteπnined using routine methods. The vector may also be administered by injection as a composition with suitable carriers including saline, dextrose, or water.
Injectable preparations, such as sterile injectable aqueous or oleaginous suspensions, may be formulated according to the known are using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally acceptable diluent or solvent, for example as a solution in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed, including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid find use in the preparation of injectables.
A suitable topical dose of active ingredient is administered one to four, preferably two or three times daily. For topical administration, the compound may comprise from 0.001% to 10% w/w, e.g., from 1% to 2% by weight of the formulation, although it may comprise as much as 10% w/w, but preferably not more than 5% w/w, and more preferably from 0.1% to 1% of the formulation. Formulations suitable for topical administration include liquid or
semi-liquid preparations suitable for penetration through the skin (e.g., liniments, lotions, ointments, creams, or pastes) and drops suitable for administration to the eye, ear, or nose.
The pharmaceutical compositions may be made up in a solid form (including granules, powders or suppositories) or in a liquid form (e.g., solutions, suspensions, or emulsions). The pharmaceutical compositions may be subjected to conventional pharmaceutical operations such as sterilization and/or may contain conventional adjuvants, such as preservatives, stabilizers, wetting agents, emulsifiers, buffers etc. Solid dosage forms for oral administration may include capsules, tablets, pills, powders, and granules. In such solid dosage forms, the active compound may be admixed with at least one inert diluent such as sucrose, lactose, or starch. Such dosage forms may also comprise, as in normal practice, additional substances other than inert diluents, e.g., lubricating agents such as magnesium stearate. In the case of capsules, tablets, and pills, the dosage forms may also comprise buffering agents. Tablets and pills can additionally be prepared with enteric coatings. Liquid dosage forms for oral administration may include pharmaceutically acceptable emulsions, solutions, suspensions, syrups, and elixirs containing inert diluents commonly used in the art, such as water. Such compositions may also comprise adjuvants, such as wetting sweetening, flavoring, and perfuming agents.
The compositions of the present invention may be administered orally, parentally, by inhalation spray, rectally, or topically in dosage unit formulations containing conventional pharmaceutically acceptable carriers, adjuvants, and vehicles. The term parenteral as used herein includes, subcutaneous, intravenous, intramuscular, intrasternal, infusion techniques or intraperitoneally. Suppositories for rectal administration of the drug can be prepared by mixing the drug with a suitable non-irritating excipient such as cocoa butter and polyethylene glycols that are solid at ordinary temperatures but liquid at the rectal temperature and will therefore melt in the rectum and release the drug.
The following Examples are for illustrative purposes only and are not intended, nor should they be construed as limiting the invention in any manner. Those skilled in the art will appreciate that variations and modifications can be made without violating the spirit or scope of the invention.
EXAMPLES Example 1 Materials and Methods A. Cell Culture and Brain Tumor Specimens.
All established human brain tumor cell lines were maintained using Dulbecco's modified Eagle's medium (DMEM, containing 4.5 g/L glucose) supplemented with 10% heat- inactivated fetal bovine serum (FBS) (Whittaker BioProducts, Walkersville, MD). The
following cell lines were used for analysis: Human glioblastoma, SNB-19 and D-54MG (generously provided by Dr. Paul Kornblith, Univ. of Pittsburgh and Dr. Darrell Bigner, Duke University, respectively); Human glioblastomas, U-87MG, U-373MG, U-118MG, and SW1088 (American Type Culture Collection (ATCC), Rockville, MD); Human neuroblastoma cell lines, SKN-SH, SKN-MC and IMR 32 (ATCC), and LAN-5 (generously provided by Dr. Stephan Ladish, Children's Research Institute, Washington DC); Human hepatocarcinoma, Hep G2 (ATCC) as a positive control for GnT-V. A panel of surgical specimens was used that consisted of 13 gliomas: 1 astrocytoma grade II, 1 high-grade oligodendroglioma, 1 mixed glioma, 3 cases of astrocytoma grade III and 7 cases of astrocytoma grade IV, i.e. glioblastoma, (WHO Brain Tumor Classification).
To study protein kinase C (PKC)-mediated GnT-V mRNA induction, SNB-19 cells were treated with 150 nM Phorbol 12, 13-dibutyrate (PDBu, Sigma Chemical Co.) for up to 24 hr, and 15 μM 2'-amino-3'-methoxyflavone (PD 98059, Calbiochem) was used to inhibit mitogen-activated protein kinase kinase (MAPKK) (Alessi, et al. PD098059 is a specific inhibitor of the activation of mitogen-activated protein kinase kinase in vitro and in vivo. J. Biol. Chem., 270: 27489-27494, 1995.).
B. MMP cDNA and Probes
Human MMP cDNAs expressed in human glioma cell lines were cloned by using the reverse-transcriptase-polymerase chain reaction (RT-PCR). Poly A+ RNA was isolated from D-54MG and U-373MG human glioma cell lines and used for RT-PCR. Based on the consensus sequences among MT-MMPs and MMPs, degenerate MMP primers, a sense degenerate primer 5'-GTG/TGCT/AGT/CC/TCATTGGCCAC-3' (SEQ ID NO. 34) and an antisense degenerate primer 5'-GGC/AAGXG/CC/AYYGCCA-3' (SEQ ID NO. 35), were used for the PCR under standard conditions (35 cycles of 96°C denaturation, (30 seconds) / 55°C annealing (60 seconds) / 72°C polymerization (60 seconds), and a final extension at 72°C for seven minutes, hold at 435 cycles 4°C). Within the degenerate oligonucleotides, a "/" between two bases indicates the site is degenerate for the bases on either side of the "/" (i.e., G/T indicates G or T occupies that position), " Y" represents a C or T and "D" or "X" represents A, G or T. The PCR-amplified product (about 400 base pairs) was subcloned into pCR2.1 vector (Invitrogen, Carlsbad, CA), and the cDNA insert of the individual clones were sequenced. Clones were identified that contained sequence corresponding to MMP-1 (SEQ ID NO. 24), MMP-3 (SEQ ID NO.25) and MMP- 10 (SEQ ID NO. 26), and these were used for Northern analysis.
C. Ets-1 cDNA and Probes
Human Ets-1 cDNA was also cloned using RT-PCR and poly A+ RNA from U-87 MG cells based on the sequence reported previously (Wasylyk, et al. The c-ets proto-
oncogenes encode transcriptional factors that cooperate with c-fos and c-jun for transcriptional activation. Nature (London), 346: 191-193, 1990.). A sense primer 5'- TTGGGAAGAAAGTCGGATT-3' (bp -119 to -101; SEQ ID NO. 6) and an antisense primer 3'-CAGGCTGAATTCATTCACAGC-5' (bp 270 to 250; SEQ ID NO. 7) were used for RT-PCR under standard conditions (35 cycles of 96°C denaturation, (30 seconds) / 55°C annealing (60 seconds) / 72°C polymerization (60 seconds), and a final extension at 72°C for seven minutes, hold at 435 cycles 4°C). A 398 bp PCR product (SEQ ID NO. 5) was cloned into pT7 Blue T vector (Novagen, Madison, WI) and the sequence of the insert was confirmed by the dideoxy termination method (Sequenase, United State Biochemical, Cleveland, OH). The ets-1 cDNA insert was isolated from the gel after Nde I and Bam HI digestion and was used as a cDNA probe.
D. GnTV cDNA and Probes
A 1.24 kb human GnT-V cDNA (GenBank Accession No. D17716; SEQ ID NO. 36) was isolated after Eco RI restriction digestion and was also used as a cDNA probe for Northern analysis. The amino acid sequence of GnT-V, encoded by nucleotides 146-2371 of SEQ ID NO. 36, is shown in SEQ ID NO. 37.
E. uPA cDNA and Probes Human uPA cDNA was cloned using RT-PCR and polyA+ RNA isolated from U-
87MG glioma cells based on the sequence reported previously (GenBank Accession No. A18397; DNA sequence shown in SEQ ID NO. 38; amino acid sequence encoded by nucleotides 100-1395 of SEQ ID NO. 38 is shown in SEQ ID NO. 39). Primer A, TTGTTGTGTG GGCTGTGAGT (SEQ ID NO. 40) and Primer B, ACTGGCCAAGAAAGGGACAT (SEQ ID NO. 41) were used for RT-PCR under standard conditions (35 cycles of 96°C denaturation, (30 seconds) / 55°C annealing (60 seconds) / 72°C polymerization (60 seconds), and a final extension at 72°C for seven minutes, hold at 435 cycles 4°C). A 408 bp PCR product was cloned into pCR2.1 vector (Invitrogen, Carlsbad CA) and the sequence of the insert was confirmed (SEQ ID NO. 42). The cDNA insert was isolated from the agarose gel after Eco RI restriction digestion and was used as a cDNA probe for Northern analysis.
F. Procedure for northern blot
Surgical specimens were immediately frozen in liquid nitrogen upon resection. Total RNA was isolated from clinical glioma specimens and cultured brain tumor cells using guanidium isothiocyanate followed by CsCl2 centrifugation as described previously (16). 30 μg of total RNA per primary brain tumor and 20 μg of total RNA per tumor cell line per lane were electrophoresed in an agarose-formaldehyde gel and transferred to Duralon nylon
membranes (Stratagene, La Jolla, CA). After UV cross-linking, the blots were hybridized with a 32P-radiolabeled cDNA probe synthesized by using a random priming kit (Stratagene, La Jolla, CA) and ExpressHyb solution (Clontech, Palo Alto, CA). The blots were then exposed to X-OMAT film (Kodak, Rochester, NY) and the films were developed appropriately.
G. Procedure for western blot
To detect Ets-1 protein expression in brain tumor cell lines, 20 μg of protein cell lysates were loaded on a 8% SDS-polyacrylamide gel immediately after boiling each sample in the presence of 2% mercaptoethanol. After electrophoresis, proteins were transferred to a PVDF membrane and the membrane was blocked with 5% BSA in PBS. It was then incubated with a 1: 10,000 dilution of monoclonal anti-human Ets-1 antibody (Clone 47, Transduction Laboratory, KY) in Tris-buffered saline pH 7.4 (TBS) containing 2% BSA and 0.1 % Tween 20 for 1 h at room temperature. The membrane was then washed with TBS containing 2% BSA and 0.1 % Tween 20 for 10 min, followed by washing twice with 0.1 % Tween 20 in TBS. Next, it was incubated with a 1:10000 dilution of horseradish peroxidase- conjugated anti-mouse IgG (Amersham, UK) for Ih at room temperature in 2% BSA in TBS containing 0.1 % Tween 20. The membrane was then washed as described above, and developed with the ECL Chemiluminescence detection system (Amersham, UK) according to manufacturer's instructions.
This skilled artisan would understand this technique to be applicable using another antibody, such as an antibody reacting with GnTV, by interchanging the ets-1 antibody with the GnTV antibody. Antibodies to other proteins of interest may also be utilized. For example, an antibody to uPA is available from American Diagnostica (Greenwich, CT; product number 3689/398), MMP-1 antibodies are available from Lab Vision Corporation (Freemont, CA; see, for example, clone X2A, clone VI3, clone COMY 4A2, clone 1117, and/or clone III12B), and MMP-3 antibodies are available from Lab Vision Corporation (Freemont, CA; see, for example, clone SL-1 ID3, clone SL-1 IID4, clone SL-1 IIIC4, and/or clone SL-1 IVB1).
Example 2 Expression of GnT-V and ets-1 in human brain tumor cell lines A. Expression of GnT-V and ets-1
GnT-V and ets-1 mRNA expression was studied in a panel of six glioma and four neuroblastoma human brain tumor cell lines. Eight of ten cell lines expressed both GnT-V and ets-1 mRNA, and the levels of gene expression were well correlated. Those cell lines with high levels of GnT-V mRNA expression showed robust ets-1 mRNA expression, while the SNB-19 glioma and SKN-MC neuroblastoma cell lines showed very low expression of
both GnT-V and ets-1 mRNA (Figure 1 and Table 1). A western blot showed that the 51 kDa Ets-1 protein was expressed uniformly in the entire panel of brain tumor cell lines examined (Figure 2).
This contrasts with previous data suggesting that Ets-1 protein was absent within carcinoma cells (Wernert, et al. Stromal expression of c-Etsl transcriptional factor correlates with tumor invasion. Cancer Res., 54: 5683-5688). This surprising difference in terms of Ets-1 protein expression within tumors may be due to the fact that the stromal reaction by fibroblasts plays an important role in carcinoma invasion, while there is little stromal reaction in malignant gliomas. The data suggests that in glioma Ets-1 expression may play a direct role in promoting cancer and, in particular, in glioma invasion. It also has been reported that the expression of Ets-1 can be modulated by growth factors and PKC activators (Wernert, supra), such as phorbol ester, through its interaction with other transcription factors, such as AP-1 (Wasylyk, et al. The c-ets proto-onco genes encode transcriptional factors that cooperate with c-fos and c-jun for transcriptional activation. Nature (London), 346: 191-193, 1990; Uhm, et al. Mechanisms of glioma invasion: Role of matrix-mettalloproteinases. Can. J. Neurol. Sci, 24: 1-15, 1997.). Those studies suggest that the MAP kinase pathway and Ets-1 play a role in the expression of GnT-N in glioma cells.
B. Expression of MMPs. MMPs were expressed in D-54MG and U-373MG human glioma cell lines using RT-
PCR with MMP degenerate primers as described above. Following amplification, 34 clones were isolated and the DΝA sequences of each analyzed. Of the 34 clones, DΝA sequences of 6 clones were identical to that of MMP-1; 18 clones were MMP-3, and 2 clones were MMP- 10. Northern analyses was performed to examine mRNA expression in a panel of human brain rumor cell lines. Both MMP-1 and MMP-3 were expressed in SW-1088, U-87MG and U-118 glioma cell lines and in SKN-SH neuroblastoma cells, while D54-MG glioma cells expressed low levels of MMP-3 with no MMP-1 expression (Figures 3 A and 3B). Neither MMP-1 nor MMP-3 was expressed in U-373 MG or SNB-19, and three other neuroblastoma cell lines showed no MMP expression. MMP-10 expression was found only in SW1088 and U-87MG glioma cell lines (Figure 3C), which express high GnT-N mRΝA. No MMP-10 mRNA expression was found in neuroblastoma cell lines. MMP-1 and MMP-3 mRNA expression was primarily associated with cell lines which showed high ets-1 expression, except in U-373MG glioma and LAN-5 neuroblastoma cell lines. No MMP mRNA expression was found in SNB-19 glioma or IMR32 and SKN-MC neuroblastoma cell lines, all of which expressed little ets-1 mRNA. Unlike GnT-V mRNA expression, the levels of MMP expression were not directly correlated with the levels of ets-1 mRNA expression in those cell lines.
TABLE 1
Expression of Ets-1, GnT-V, MMP-1, MMPS and MMP-10 in Cell Lines1
very low level to absence of expression.
Example 3 Identification of a compound that up-regulates expression of ets-1, GnT-V, MMP-1 and
MMPS in cancer cells
It has been previously demonstrated that Ets-1 controls GnT-V transcription in human bile duct carcinoma HuCC-Tl cells (Alessi, et al. PD098059 is a specific inhibitor of the activation of mitogen-activated protein kinase kinase in vitro and in vivo. J. Biol. Chem., 270: 27489-27494, 1995) and that ets-1, MMP-1 and MMP-3 mRNA expression can be modulated by growth factors and PKC activators such as phorbol ester in human fibroblast cells (Wernert, et al. Stromal expression of c-Etsl transcriptional factor correlates with tumor invasion. Cancer Res., 54: 5683-5688, 1994).
An assay was developed to identify compounds that increase expression of a panel of nucleic acids in a cancer cell. It should be understood that it is not absolutely necessary that each sequence in the panel be assayed. It is possible, for example, that analysis of ets-1
expression alone would be sufficient. In this example, the panel of sequences comprises ets- 1, GnT-V, uPA, MMP-1, and MMP-3.
Resting SNB-19 glioma cells were utilized for the model system because expression of MMPs, GnT-V or ets-1 mRNA is virtually absent (Figures 1 and 3). Low levels of uPA expression are observed in SNB-19 cells. As a test compound, the effects of a phorbol ester (a Protein Kinase C (PKC) activator) on the coordinated expression of a panel of sequences was determined. SNB-19 cells were cultured in the presence of 150 nM phorbol 12, 13- dibutyrate (PDBu, Sigma Chemical Co.) for 24 hr. Expression of GnT-V, c-ets-1, uPA, MMP-1 and MMP-3 was then assayed by northern blot on total RNA from the cells. A panel of nucleic acid probes corresponding to GnT-V, c-ets-1, uPA, MMP-1 and MMP-3 were prepared as described above and utilized to detect expression of the corresponding mRNA in treated or untreated SB- 19 cells. As shown in Figure 4, mRNA expression for each member of the panel (MMP-1, MMP-3, GnT-V and ets-1) was induced following a 24 hour exposure to PDBu. Thus, PDBu is a compound that induces expression of GnT-V, c-ets-1, uPA, MMP- 1 and MMP-3 in glioma cells.
In a similar manner, this assay is useful for the identification of other compounds that induce expression of GnT-V, c-ets-1, uPA, MMP-1 or MMP-3. The cells are incubated with the compound to be tested and expression of GnT-V, c-ets-1, uPA, MMP-1 and/or MMP-3 is analyzed. A compound that is found to induce expression of any, multiple or all of these sequences is one that may induce tumor cell activity, including invasion, in a patient. In such a case, the compound is probably not a candidate for treatment of the patient.
Example 4 Assay for Identification of Compounds for Inhibition of Gene Expression in Cancer Cells As described above, the assay is useful for identifying compounds, such as PDBu, that increase expression of GnT-V, c-ets-1, uPA, MMP-1 or MMP-3. A modified version of the above-described assay is also useful for the identification of compounds that can inhibit expression of the sequences. To identify compounds that may affect the growth, migration or invasivity of tumor cells, the assay described below is provided. SNB-19 glioma cells are cultured in the presence of 150 nM Phorbol 12, 13-dibutyrate (PDBu, Sigma Chemical Co.) for 24 hr. The cells are then contacted with a test compound that may affect expression of GnT-V, c-ets-1, uPA, MMP-1 or MMP-3. Compounds shown to inhibit expression of any, multiple or all of the sequences are selected for further study.
An example of such a system is shown below. SNB-19 cells were pre-incubated in the presence of 150 nM Phorbol 12, 13-dibutyrate (PDBu, Sigma Chemical Co.) for 24 hr. The PDBu was then washed out of the culture medium by exchanging the media containing PDBu with fresh media. The pre-incubated cells were then contacted with 15 μM 2'-amino- 3'-methoxyflavone, a MAPKK inhibitor (PD 98059, Calbiochem; Alessi, D. R., et al.
PD098059 is a specific inhibitor of the activation of mitogen-activated protein kinase lanase in vitro and in vivo. J. Biol. Chem., 270: 27489-27494, 1995). The compound was incubated with the cells for 24 hours and the cells were harvested. Total RNA was then isolated from the cells and a northern blot was performed. A panel of probes corresponding to GnT-V, c-ets-1, uPA, MMP-1 and MMP-3 were prepared and utilized to detect mRNA expression in SB- 19 cells. The coordinated induction of GnT-V, c-ets-1, MMP-1, and MMP- 3 transcription induced by PDBu was completely abolished by PD 98059 (Figure 4). uPA expression was decreased in a dose-dependent manner (Figure 4). Thus, a compound having the ability to affect gene expression in phorbol ester-stimulated cells was identified. In a similar manner, this assay is useful for the identification of other compounds that inhibit expression of GnT-V, c-ets-1, uPA, MMP-1 or MMP-3. This is most likely a desirable characteristic of a compound being considered for use as a chemotherapeutic agent. To identify such a compound, the phorbol ester pre-inucubated cells are contacted with the compound to be tested and expression of GnT-V, c-ets-1, uPA, MMP-1 and/or MMP-3 is analyzed as described above. A compound that is found to inhibit expression of one or more of these sequences may then be selected as a candidate compound for inhibition of tumor cell activity, such as invasion, in a patient. In such a case, the compound is likely a useful candidate for treatment of the patient.
Example 5
Identification of Nucleic Acids Induced by Ets-1 A. Development of inducible ets-1 cell line
A model system was developed with which nucleic acids and other factors (i.e., compounds) that are induced by or affect expression of ets-1 expression may be identified. A cell line was developed that includes an inducible ets-1 construct stably transfected into the genome of the cell. In this model system, ets-1 expression can be induced by addition of tetracycline and the resultant effects on the cell measured. The effects may include induction of gene expression or alteration of protein activity, for example. Construction and use of an exemplary cell line is described below. The 1.4 kb human c-ets-1 (full coding sequence) (SEQ ID NO. 1) was inserted between the Kpnl and Xhol sites of the pcDNA4/TO vector (Invitrogen, Carlsbad, CA). The pcDNA4/TO/c-ets-l and pcDNA6/TR (Invitrogen, San Diego, CA) vectors were co- transfected into human glioma SNB-19 cells using the cationic liposome system, DOTAP, essentially as indicated by the manufacturer (Boehringer Mannheim, Indianapolis, IN). After 3 weeks of culture in selection medium containing 10 μg/ml of Blasticidin and 1 mg/ml of Zeocin, transfected cells were subcloned with cloning rings to isolate individual clones. Individual clones were further cultured for 4 weeks in the selection medium and then analyzed for the regulated gene expression in the presence of 2 μg/ml tetracycline.
B. Use of the inducible ets-1 cell line to identify nucleic acids influenced by ets-1
It has previously been demonstrated that ets-1 influences the expression of GnT-V (Kang, et al. Transcriptional regulation of the N-acetylglucosaminyl-transferase V gene in human bile duct carcinoma cells (HuCC-TO is mediated by Ets-1. J. Biol. Chem., 271: 26706-26712, 1996; Ko, et al. Regulation of the GnT-V promoter by transcription factor Ets- 1 in various cancer cell lines. /. Biol. Chem., 274: 22941-22948, 1999.). GnT-V and uPA were selected as test sequences to demonstrate the identification of nucleic acids influenced by ets-1 using the inducible ets-1 cell line. As shown in Figure 5, ets-1 expression in the SNB-19 ets-1 inducible cell lines B3, B7, B9 and A15 transfectants resulted in the increased expression of GnT-V mRNA as determined using a GnTV probe (SEQ ID NO. 20 or 21) and uPA mRNA using a uPA probe (SEQ ID NO. 42). Thus, as shown herein, the inducible ets- 1 cell lines are useful for identifying nucleic acids that are affected by ets-1.
Th inducible ets-1 cell line is useful for the identification of sequences, proteins or other factors that are affected by ets-1. The inducible ets-1 cell line is also useful for identifying compounds the interfere or activate the ets-1 regulatory pathway by inducing ets-1 expression, treating the induced cells with a compound, and assaying the effects on the ets-1 regulatory pathway (i.e., gene targets of ets-1).
Example 6
Identification of Ets-1 Induced Nucleic Acids Using a DNA Chip
A DNA chip can be utilized to identify nucleic acids that are induced by expression of ets-1 or compounds that influence the expression or function of such nucleic acids. The DNA chip may be utilized essentially as described by Harkin, et al. (Cell, 91: 575-586, 1999) or Der, et al. (Proc. Natl. Acad. Sci. USA, 95: 15623-15628, 1998), for example. Other suitable methods are available in the art.
To identify nucleic acids that are influenced by expression of ets-1, the ets-1 inducible cell line described in Example 6 above is utilized. Ets-1 expression is induced by inclusion of tetracycline in the culture media. Gene expression is then analyzed essentially as described below. It is possible to construct a gene chip comprising nucleic acids comprising sequences substantially corresponding to GnTV, c-ets-1, uPA, MMP-1, MMP-3, or MMP-10, for example, and utilize that chip for analysis. However, commercially available gene chips may also be utilized, as shown below, to obtain a broad fingerprint reflecting the influence of ets-1 on gene expression in a cell or the effects of a compound on expression. cRNA preparation, hybridization, and scanning a Hu6800 GeneChip Array is performed as described by by the manufacturer (Affymetrix; Santa Clara, CA). Poly (A)+ RNA is isolated from 100 μg total RNA of cells cultured in the presence of tetracylcine (ets-1 induced) or in the absence of tetracylcine (uninduced, control cells) with Oligotex (Qiagen)
and converted into double-stranded cDNA using a cDNA synthesis kit (Superscript Choice, GIBCO/RBL) using a an oligo (dT)24 primer containing a T7 RNA polymerase promoter site added 3 ' of the poly T tract (Genset). Following synthesis of the second strand, labeled cRNA is generated from the cDNA sample using the in vitro transcription (IT) reaction T7 MegaScript System, Ambion) supplemented with biotin-11-CTP and biotin-16-UTP (Enzo Diagnostics). The labeled cRNA is purified by using RNEASY spin columns (Qiagen). Fifty micrograms of each cRNA sample is then fragmented by mild alkaline treatment, at 94°C for 35 min in fragmentation buffer (40mM Tris-acetate, pH 8.1/100 mM potassium acetate 30mM magnesium acetate). This is then used to prepare 1 ml of master hybridization mix {0.1 mg/ml of herring sperm DNA (Sigma)/ 1 M sodium chloride/ lOmM tris, pH 7.6/0.005% Triton X-100). A mixture of four control cRNAs for bacterial and phage genes is included in the mix (BioB, BioC, BioD, and ere, at 1.5, 5, 25, and 100 pM, respectively; refen'ed to as "staggered spikes") to serve as tools for comparing hybridization efficiency between arrays and for relative quantitation of measured transcript levels. A biotinylated oligoucleotide, B2, which hybridizes to unique features at the center and four corners of each chip to facilitate accurate orientation and mapping of the probe sets is also added that hybridizes to unique features at the center and four corners of each chip, is included to facilitate accurate orientation and mapping of the probe sets.
Prior to hybridization, the cRNA samples are heated to 94°C for 5 minutes, equilibrated to 40°C for 5 minutes, and clarified by centrifugation (14,000 x g) at room temperature for 5 minutes. Aliquots of each sample (10 μg of cRNA in 200 μl of the master mix) are then hybridized to Hu6800 GeneChip arrays at 40°C for 16 hr in a rotisserie oven set at 60 rpm. The arrays are then washed with 6 x SSPE and 0.5 x SSPE, stained with streptavidin-phycoerythrin (Molecular Probes), washed again, and read using a confocal microscope scanner with the 560-nm long-pass filter (Molecular Dynamics; Affymetrix).
Data analysis is performed by using GENECHIP 3.0 software. Initial absolute analysis for gene expression is performed without scaling while subsequent comparison analysis files are created by scaling the six probe sets for 5', middle (M), and 3' of actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in all data sets to a uniform value, 50,000, and normalizing to all genes.
A comparison of the data indicates which sequences affixed to the Hu6800 Gene Chip are expressed at different levels in induced and uninduced cells. Sequences are identified that are expressed following ets-1 expression, and such sequences are characterized as ets-1 inducible sequences. The genes overexpressed in cells expressing ets-1 may be involved in the development of gliomas in a patient. Thus, this system provides targets for further development as anti-glioma therapeutics.
Using the methods described above, this system is adaptable to any type of cell line derived from any type of cancer or other condition. The scientist needs only to develop a cell
line containing the inducible ets-1 construct stably transfected into the genome of the cell, as has been described herein using the glioma cell line. Many different cell lines are available that could be used for this p pose. For example, the effects of ets-1 on gene expression in a prostate cancer cell could be determined by generating an LnCAP cell line comprising the ets-1 inducible construct. The differences in gene expression between induced and uninduced LnCAP is then determined as described above for glioma cells.
Example 7 Identification of compounds affecting ets-1 expression or function A recombinant reporter vector is constructed that incorporates a responsive element, promoter or other transcriptional control region of interest operably linked to a reporter sequence such as a nucleic acid encoding β-galactosidase (β-gal) or luciferase (LUC). Activation or inactivation of the responsive element, promoter or other transcriptional control region of interest within a cell is determined by detection of the reporter sequence. Addition of a compound to the cells transfected with the recombinant reporter vector may result in alteration of the activity of the responsive element, promoter or other transcriptional control region of interest, indicating the compound affects the function of the responsive element, promoter or other transcriptional control region of interest. Thus, compounds that activate or inhibit the function of a responsive element, promoter or other transcriptional control region of interest may be identified.
Of particular use is a promoterless reporter vector where a putative promoter sequences may be inserted upstream of a reporter sequence such as β-gal, luciferase, green fluorescent protein (GFP), yellow fluorescent protein (YFP), or red fluorescent protein (RFP), or variants thereof. Such promoterless reporter vectors are available from commercial vendors such as Clontech (Palo Alto, CA) and include but are not limited to pECFP-1, pEGFP-1, pEYFP-1, pd2EGFP-l, pDsRedl-1, and pRL-null (Promega, Madison, WI). To assay for expression of β-gal, for example, a β-gal assay is perfonned using, for example, the Luminescent β-gal Genetic Reporter System II (Clontech, Palo Alto, CA). To assay for expression of luciferase, for example, the Dual-Luciferase™ Reporter Assay System (Promega, Madison, WI) may be utilized. Asssay systems for detection of GFP, YFP and RFP are also available from commercial vendors. Other suitable assay systems may also be useful for practicing this assay.
The recombinant DNA molecule for assaying compounds preferably comprises a promoter selected from the MMP-1 promoter (SEQ ID NOS. 27 or 28, for example), MMP-3 promoter (SEQ ID NO. 29), MMP- 10 promoter (SEQ ID NO. 30), GnTv promoter (SEQ ID NO. 31), or an ets-1 promoter (SEQ ID NOS. 32 or 33) operably linked to a nucleic acid encoding luciferase ("LUC") within the pRL-null reporter vector. The Dual-Luciferase™ Reporter Assay System is utilized to detect luciferase activity.
As described above, a useful promoterless luciferase reporter vector is pRL-null (Promega). A recombinant reporter construct "pRL-Ets-1" , is constructed such that the ets-1 promoter (SEQ ID NO. 32 or 33, for example) is operably linked to a nucleotide sequence encoding β-galactosidase ("β-gal") by insertion into the EcoRI or Xhol site of pRL-null. Using standard methods, EcoRI linkers may be added onto the 5' and 3' ends of SEQ ID NO. 32 to generate the Ets-1-promoter/EcoRI insert. Alternatively, the SEQ ID NO. 32 may be amplified by PCR using primers containing EcoRI restriction sites at the 5' termini of the ets- 1 promoter PCR primers. Using either of these methods, an Ets-1-promoter/EcoRI insert suitable for insertion into the pRL-null vector is obtained. The Ets-1-promoter/EcoRI insert is then inserted into the EcoRI site of pRL-null to generate "pRL-Ets-1" . Cells may then be transfected with the pRL-Ets-1 construct using standard techniques. The cells are then contacted with a compound and expression of LUC, which is driven by activation by the ets-1 promoter, is detected. An increase or decrease in the amount of LUC expressed following contact with the compound indicates that the compound either directly or indirectly affects the ets-1 promoter. Such a compound may then be selected for further analysis as a therapeutic agent. A suitable compound for use in practicing this assay system is PDBu.
It is also possible to insert a neomycin selectable marker ("neo") into the pRL-Ets-1 construct to generate the expression plasmid pRL-Ets-1-Neo for stable transfection. In this manner, a reporter cell line is generated, where expression of LUC indicates activation of the ets-1 promoter. Mammalian cells such as SNB-19 are stably transfected with the pRL-Ets-1- Neo construct using standard techniques and cultured in the presence of neomycin. Stably transfected cells are identified following growth in the presence of neomycin. The stably transfected cells are then clonally selected and tested for LUC activity following culture in the presence of 150 nM PDBu for 24 hours (PDBu activates the ets-1 promoter, as shown herein). Clones are selected which show increased LUC activity following exposure to PDBu, indicating that the Ets-1 promoter is functionally linked to the LUC reporter sequence within the genome of the cell.
The resultant cell line is then utilized to identify compounds that activate the ets-1 promoter via a high throughput assay. Cells are cultured in the presence of an experimental compound and assayed for expression of luciferase using standard techniques. Increased luciferase expression indicates that the compound activates the ets-1 promoter. Such a compound could then be selected for further testing using the method of Example 3 above, for example.
In a similar manner, the cell line may be utilized to identify compounds that inhibit expression of ets-1. The cells are incubated in the presence of 150 nM PBDu for 24 hours. The PDBu is then washed out and a compound of interest added to the cell culture. LUC activity is then measured and compared to cells that were only exposed to PBDu and not to the compound of interest. Compounds that result in decreased expression of LUC are
potential targets for further development as chemo therapeutics. Such compounds may be further subjected to the analysis of Example 4 above, for example. Thus, an assay providing for high-throughput fluoresence-based analysis of gene expression to identify compounds that activate or inhibit the activity of the ets-1 promoter is provided. This method is further adaptable to tumor tissue isolated from a patient, where the cells are stably or transiently transfected with either the pRL-ets-1 or pRL-ets-1-neo vector, and exposed to a compound that is being considered as a chemotherapeutic agent in the patient. An increase or decrease in expression of luciferase following transfection of the reporter vector and exposure to the compound indicates that the compound probably influences ets-1 expression in the cell. Such a method may assist the physician in determining the optimal course of treatment for the patient.
Example 8 Western Blot Assay for Detection of Ets-1, GnT-V, MMP-1 and MMPS in Cancer Cells SNB-19 glioma cells are cultured and then contacted with a compound that may affect gene expression. The compound is incubated with the cells for a sufficient period of time and the cells are harvested. Total protein is then harvested from the cells and a western blot performed as described above for ets-1 (see Materials and Methods). A panel of labeled antibody probes corresponding to the Ets-1, GnT-V, MMP-1 and MMP-3 polypeptides is prepared and separately utilized to detect expression of the Ets-1, GnT-V, MMP-1 and MMP- 3 protein in the treated SNB-19 cells. An increase in the expression of a sequence of the panel indicates that the compound has an affect on gene expression in the cell. Similarly, the western blot may be utilized to detect compounds that inhibit or decrease expression of the ets-1, GnT-V, MMP-1 or MMP-3 proteins. This methodology is readily adaptable to tumor cells isolated from a patient.
Example 9 PCR-Based Assay for High Flow-Through Assay for Detection of Ets-1, GnT-V, MMP-1 and MMP-2 A PCR-based assay was developed for the identification of Ets-1, GnT-V, MMP-1 and MMP-3 transcripts in cells. To perform this assay, SNB-19 cells were cultured in the presence of 150 nM PDBu for 24 hours. Then, the following steps were performed to assay gene expression using PCR.
First strand cDNA synthesis: 1 μl of oligo dT (12-18) (500 μg/ml), 5 μg total RNA, dH20 to 12 μl were combined and incubated for 10 minutes at 70°C, followed by a quick chill on ice. 4 μl first strand buffer (Gibco), 2 ml 0.1M DTT, and 1 ml 10 mM dNTP mix were added and further incubated for two minutes at 42°C. 1 μl (200 U) of Superscript Reverse Transcriptase (Gibco) was then added and followed by incubation for fifty minutes at 42°C.
This was followed with a 15 minute incubation at 70°C, and a quick chill. 1 μl RNase A (1 mg.ml) was then added and the mixture incubated at 37°C for twenty minutes. This preparation can then be stored at 20°C, if desired.
PCR Reactions: Combine: 77.6 μl water (to equal 100 ml volume)
10 μl 10X PCR buffer (contains 1.5 mM CaCl2) 8 μl dNTP mix (2.5 mM each) 2 μl cDNA • 1 μl primer A (10 mM) 1 μl primer B (10 mM) 0.4 μl AmpliTaq polymerase 100 μl total volume The following primer pair sequences were utilized to perform the assay: (Control) H3.3 (A) 5'-CCACTGAACTTCTGATTCGC-3' (Control) H3.3 (B) 5'-GCGTGCTAGCTGGATGTCTT-3'
MMP 1 (A) 5 '-ATGCTGAAACCCTGAAGGTG-3 ' (SEQ ID NO. 10) MMP1 (B) 5'-TCCTCCAGGTCCATCAAAAG-3' (SEQ ID NO. 11)
MMP3 (A) 5 '-AACCTGTCCCTCCAGAACCT-3 ' (SEQ ID NO. 14) MMP3 (B) 5 '-CTTATCCGAAATGGCTGCAT-3 ' (SEQ ID NO. 15)
MMP 10 (A) 5 '-TGCCATTGAGAAAGCTCTGA-3 ' (SEQ ID NO. 18)
MMP 10 (B) 5 '-GGGGAGGTCCGTAGAGAGAC-3 ' (SEQ ID NO. 19)
GnTV (A) 5 '-TGTTCCCTCATACCCCAGAC-3 ' (SEQ ID NO. 22)
GnTV (B) 5 '-GCTGGGATGTCAGCTCTCTC-3 ' (SEQ ID NO. 23)
Ets-1 (A) 5'-TCCAGACAGACACCTTGCAG-3' (SEQ ID NO. 3)
Ets- 1 (B) 5 '-TTCCTCTTTCCCCATCTCCT-3 ' (SEQ ID NO. 4)
Cycling: denature at 96°C / 1 min. denature at 96°C / 30 sec.
40 cycles anneal at 55°C / 60 sec.
extend at 72°C / 60 sec.
Final extension at 72°C for 7 minutes
Hold at 4°C.
Analyze PCR products on 1.5% agarose gel. The expected amplicon sizes are: H3.3 (control for cDNA integrity) = 213 bp; MMP-1 = 299 bp; MMP-3 = 353 bp; MMP-10 = 404 bp; GnTV = 450 bp; ets-1 = 496 bp.
The results of the assay are shown in Figures 6 and 7. As shown therein, the PCR- based assay provides sensitive detection of the increase in expression of MMP-1, MMP-3, MMP-10, GnT-V, and ets-1 following incubation with the phorbol ester. Importantly, the PCR-based assay detected increased expression of MMP-10 in addition to MMP-1, MMP-3, GnT-V and ets-1, as detected by the northern blot assay described above. Thus, the PCR- based assay provides increased sensitivity over the northern blot assay. This PCR-based assay is adaptable for identification of compounds affecting expression of these sequences in cells, as described above in Examples 3 and 4, where the northern blot was utilized. Furthermore, this assay is amenable to high throughput analysis of compounds and their effects on expression of these sequences in cells.
While a preferred foπn of the invention has been shown in the drawings and described, since variations in the preferred form will be apparent to those skilled in the art, the invention should not be construed as limited to the specific form shown and described, but instead is as set forth in the claims.